Lip Prints Analysis: An Observational Study

Aim: The aim of the present study is to determine the lip prints among undergraduate dental students. Introduction: Human identification is a universal process based on scientific principles mainly involving fingerprinting. Uniqueness is a strong point used in the analysis of fingerprints to convince the court of law. Even the lip prints are unique for an individual and can be used for identification purposes. Thus lip prints can be used to verify the presence or absence of a person at the scene of crime. The aim of this study is to analyse lip prints among undergraduate dental students. Materials and Methods: The study group consisted of 50 females. The materials used were Original Research Article Samudhrasri et al.; JPRI, 34(6A): 1-9, 2022; Article no.JPRI.81377 2 lipstick, a brush for applying the lipstick, and magnifying lens. Lipstick was applied evenly on the vermilion border of the lips and the pattern was studied. Results: This study of lip print pattern of 50 females revealed the following observation: No two lip prints matched each other establishing the uniqueness of lip prints and type 2(branched Y shaped grooves) is most commonly seen. Conclusion: This study showed that lip prints are unique for an individual and hold potential promise as a supplementary tool in forensic odontology.


INTRODUCTION
Fingerprints, postmortem reports and late DNA Fingerprinting have been successful in personnel identification in the field of forensic science. Just like these methods lip prints can be instrumental in identifying a person and can be used to verify the presence or absence of a person at the scene of crime [1,2]. The wrinkles and grooves on labial mucosa called as sulci labiorum forms a characteristic pattern called as lip prints and the study of which is called cheiloscopy. This is unique to an individual just like fingerprints [3] and does not change during the life of the person [4]. It can be obtained at the crime scene from clothing, glasses, cigarettes, windows and doors. lip prints are invariable and permanent. Fischer was the first anthropologist to describe the furrows on the red part of the human lips. The use of lip prints was first studied as early as in 1932 by Edmond Locard, one of France's greatest criminologists. Apart from identifying and evidential use lip prints may also be used in detection work being the source of tactical and criminalistic information. Research studies and information regarding the use of lip prints as evidence in personnel identification and criminal investigation in forensic dentistry are very much scanty but exist as a methodology in forensic dentistry. Lemoyne snyder in his book homicide investigation written in 1950 mentions the possible use of lip prints in the identification of the individual [5].
1. Lip print identification is acceptable within the forensic science community as a means of positive identification. 2. Lip print identification methodology although rarely used is very similar to fingerprint and is an accepted form of scientific comparison. 3. There is no dissent in the forensic science community with regard to other methodologies used or the fact that lip prints provide a positive identification.
The prime objective of the present study is to determine the lip prints of the undergraduate dental students.

MATERIALS AND METHODS
The study sample comprised 50 students of a private dental college (50 females aged around 18-20 years). Care was taken to select individuals having no lesions on the lips, lip scars, lip deformities and individuals with known hypersensitivity to lipsticks were not included in the study.
A Dark coloured smudge free red lipstick was applied with a single stroke evenly on the vermilion border. The subjects were asked to rub both the lips to spread the lipstick. After about two minutes a lip impression was made on the paper. This served as the permanent record.Lateral parts of both upper and lower lips were not used in the study as they had very fine lip grooves and some exhibited immediate tapering.This impression was subsequently visualised with the use of magnifying lenses. The number of lines and furrows present, their length, branching and combinations were noted.The lip prints were coded keeping in account the name of the respective individuals.
In this study we followed the classification of patterns of the lines on the lips proposed by Tsuchihashi (Fig. 1).

. Represents the zones of the lips
For classification the middle part of the upper and lower lips was taken as the study area. Since this fragment is almost always visible in any trace the determination of the pattern depends on numerical superiority of properties of the lines on this study area. The results obtained were verified from the coded data collected at the beginning of the study. The Data was transferred to the excel sheet and was analysed using SPSS software version 23.

RESULTS
The study of lip print pattern of 50 females revealed the following observation: 8% of the students are in the age 17, 48% of the students are in the age 18, 32% of the students are in the age 19 and 12% of the students are in the age of 20 (Fig. 5).26% of the students showed type 1 lip print,8% of the students showed type 1' lip print, 64% of the students showed type 2 lip print and 2% of the students showed type 5 lip print (Fig. 6).

DISCUSSION
Lip prints are very useful in forensic investigation and personal identification. They are considered to be the most important forms of transfer evidence and are analogous to finger prints [26,27]. In the present study 50 females who are around the age group of 17-20 years were taken and their pattern of lip prints was studied.26% of the students showed type 1 lip print,8% of the students showed type 1' lip print, 64% of the students showed type 2 lip print and 2% of the students showed type 5 lip print. It is also found that no two lip prints matched each other.
Lip prints are usually left at crime scenes and can provide a direct link to the suspect. In recent years lipsticks have been developed that do not leave any visible trace after contact with surfaces such as glass, clothing, cutlery or cigarettes [4]. These lip prints are characterised by their permanent nature and referred to as persistent lip prints. Although invisible lip prints can be determined using materials such as aluminium powder and magnetic powder [5,28] the use of lipsticks is not indispensable for leaving lip prints.
The edges of lips have sebaceous glands with sweat glands in between. Thus the secretion of oil and moisture from these enable development of latent fingerprints analogous to latent fingerprints [29,30]. In a previous study it is stated that type 1 and type 1' lip prints are dominant in females [31]. lip morphology do not vary significantly between the genders but the pattern varies. Even though the lines and furrows are present both in the upper lip and the lower lip from one corner of the mouth to the other corner, only the middle portion of the lip is taken into account since this portion is visible in any traces. In this study we studied a particular pattern on the basis of numerical superiority of types of lines present that are vertical, intersected, branched or reticular. If more than one pattern predominates it is taken as undetermined (type 5). In the present study type 2 is found to be dominant in females which is in accordance with a similar study done by Neha bansal, et al in a study sample of 2500 females and 2500 males stated that Type I, I', II lip print pattern was most predominant in females [32]. It is found in the study that lip prints are unique to each individual and a similar study done by Amrita, et al in a study sample of 200 medical students also stated the same [33].
The limitations of the study is Lip prints usually recover from minor trauma but surgery and pathosis can alter the pattern of the grooves. As the sample size is less it does not represent the entire population. Future studies can be done in different age groups and comparing both the genders as lip prints can be used in gender determination. Sample size can be increased for more accurate results.

CONCLUSION
The present study is able to convey that type 2 lip print is predominant in females and lip prints are unique for an individual. Though the result obtained by the present study isn't convinced to be an infallible method nevertheless it does seem to go one step closer to the truth that lip prints hold potential promise as a supplementary tool alongside with other modes in forensic odontology. Research studies and knowledge regarding the use of lip prints as evidence in personal identification and criminal investigation in forensic dentistry are considered scanty, but exist as a methodology in forensic dentistry .Studying in depth and establishing further facts and truth in lip prints will certainly help as useful evidence in forensic dentistry.

CONSENT
As per international standard or university standard, patients' written consent has been collected and preserved by the author(s).

ETHICAL APPROVAL
As per international standard or university standard written ethical approval has been collected and preserved by the author(s).

SOURCE OF FUNDING
The present project is supported by